Blind landing indicator and controller for aircraft



Oct. 7, 1952 o. E. EsvAl. 2,513,050

BLIND LANDING INDICATOR AND CONTROLLER FOR AIRCRAFT Filed Feb. 5. 1947 2 SHEETS- Smm 1 Oct. 7, 1952 0, E, ESVAL 2,613,050

BLIND LANDING INDICATOR AND CONTROLLER FOR AIRCRAFT Filed Feb. 5, 1947 2 SHEETS- SHEET 2 euA/wAY&BEAc0/v T0 Ill I HI Hl lNvr-:NTOR OHMI/v0 E. `ES VAL Patented Oct. 7, 1952 UNITED ,STATES PATENT iO-F FICE BLIND LANDING INDICATGRAND CON- I TROLLERFOR AIRCRAFT' v Orland Esval, :Huntington: Y., ,assgnorto ,ThevSperry Corporation, acorporation of Dela- .Ware

ApplicationLFebr-uary 5, 1947,;:Serial'No.f726;605 1s claims. (einzu-+71) This Ainventionrelates 'to .radio blind landing ,zon. fThe-result1s thatfa blind landiller Operation jhas 'becomeonerof the most diicult flying profoedures and .isonlyattempted under blind flying conditions-by the vmost skillful and experienced .pilots ,and is avoided wheneverpossible.

According v to .the present invention a. unitary instrument is provided for use in blind landing on whichiis shown clearlyhow .the aviatorshould fly, either up orgdovvn or right or left to maintain the Aplane von the glide path and localizery beams `'and atv the same timethere isgshown the true attitude of; the plane so fthat .the aviator A,may at .all timesknow exactly what attitude the plane is .infand hence avoid getting into a dangerousattitude-.in blindly following la radio fcross pointer `meter.

To accomplish thiszpurpose, I propose that after setting his correctapproachairspeed, the avia- .-tor, .in .conducting va Vblind landin g,f;need `observe ,only asingle instrument; `Such as,l `an attitude gyroscope-,ora single facerepresenting an attitude gyroscope and having crossed horizontal and verticalmarkingsfon the faceof awhich there is fprovidedfV an a auxiliary bar; or index icontrolledfin .barile by ther localizerfgbeamgandainepitchlibyxzihe (glide ,xpath lbeam. ,/locordingj :tojithis instrument when the plane -gets above or below :the glide path beam, adown or up signal.tszshownbythe aforesaid tindex; on the attitude fgyro, 4l.causimgithe fai/ fiator to attemptto restore the auxiliary bar.,.to ritslnormal 4position incl-ine. .with-fthe equatorfzon the `stabilized fsphere. lSimilarly :las *the plane -departs ,ato the right or zleftlof the :localizer lbeam, this bargisytiltedor ffbanked inlagdirectionfzand amount;-` sucnnthat theaviatorin ..attemptmgA lto -apparentlyxright the planef puts inla Kbank in. :the apropera'direction and -.a :proper '..amountzto I' turn "the craft lb ack into ithe`I [locali-zer lbeam. smoothly zandzfwithout l overshooting.

Preferably the A signals fedl intozthe -.controller lotthezauxlary Atindex 2in bank: area combination .-ofA-.a ydisplace mentl signal; thatgis; a signaliproportional-.to-Lthe displacementvof the craft 'laterally .from v#cherlocalizer. -beam,combi ned lwith ;a second iunctlonofl .the fraterna .change "',2 .of ,such displacement. By. .combining .these two factors anlasymptoticapproach to the beam may be iachieved. v K

:According-to .a. .modication, the Ysecond signal fed into; my blind'landingindicator to cause tilt ofthe auxiliary bark maybe function .of the di-ierence Afbetweenthe runway .direction and ycom-- Apass' heading of .the craft, .of which,` in the final analysis the rate of change of displacementisfa `function.

In-additionto or .in .lieu of employing :my inventionas anattitudefindicatorand course changer, .it .likewiseris readilyadaptedto .control an autovvmatic-pilot .foraircraftto guide Vit along a radio .deiined-fcourse. My invention .isalsonot necessarily :limited to .being used in blindflanding. .or in radioappmaches .tolandingiielda but may be employed throughout yaiiight for. maintaining the .craft -on va radio ,defined course, if desired'.

Referring -tofthe drawings showing .the several forms of my.invention abovedescribed c Eig. l isa perspective 4`view `of my blind .landing indioatonshowing alsoqa wiringdiagram of the inputto the same fro-mfglide. pathfand localizer zbeamS;

Fig..,..2-sho.wsamoded .method of obtainingr Ythe;.input ..toy .such an indicatorv from. a position maintaining ldeviee,ll ig.2 also showing a wiring diagram of an automatic pilot .system showing howfthefsamelwould-.belcontrolled from both the .attitudeggyro oflig. land the .directional gyru- Vscope .-or gyromagnetiogcompass during normal .flight and fron1 the' attltude gyroscopealone (as Airl-iluenced byi the. radioiglide .path and .localizer beams) .duringblind landings-operations.

My `improved xindicaton.rnay :utilize anyv known type tof; gyroscopically ystabilized artificial horizon orlgyroscopethe-type.shown'being of the form ldescribed fin the prior gpatentapplication of Wrigvley, EsvaLand HaskinsSerial No. 636,384, led lDecember 21,r 1.945; forr Attitude Gyros.

According to this system, the sensitive'element vpreferably consists lof a rotor (not shown) mounted for.l spinning abouta normally vertically :spinningaxiswithin rotor casing l. The casing lis mounted for .oscillation about a transverse axis -12 infthegimbalring,.whichmay be U-shaped toaiorda full View .of the indications from the instrument. Gimbal ring, in turn, isgmounted forfreedomabout a forefand-.aftaxis `Zfby means oflong trunnion ly-mountedin spaced .bearings llland V6. -The casing l maybe lformed as, .or

enclosed within, a hollow truncated sphere 1 on which latitude gradua tionsV 8 ,are placedwith a l: .Central ..eouatorial marking f9- -Preferab1y :the

lower half of the sphere is of different color from the upper half. The fixed reference bar LIS extends across the face of the instrument so that pitch is indicated by the up and down movements of the equator or horizon marking S and the graduations 8 with respect to the reference I0 and roll by the tilt of the equator or horizon marking 9 with respect to the reference IU.

On such an attitude gyroscope, I provide an additional reference index II, which may be colored differently from index IIJ, as for instance, by being made red, while the index I is checked black and white. Index II normally lies in a horizontal line with the equator 9 and the reference I0, but the position of the index I I is controlled in pitch from the radio glide path receiver and in roll from the localizer beam. To accomplish this, the index II is pivoted independently of the gyroscope. it is pivoted about an axis I2 in a second gimbal I3, the axis I2 normally being in line with the aforesaid axis 2 of the rotor frame. The gimbal I3, in turn, is pivoted in bank by having a long sleeve bearing It at the rear journalled in spaced bea-rings I 6, I'I in the fixed support I5 in the instrument case (not shown). A centralizing spring 50 is shown to hold gimbal I3 and its attached index athwartship or normally horizontal.

The pitch of the bar I I is governed by a motor I8 of the torque or meter type, operating against a centralizing spring 'I 8. The input to the motor I8, in turn, is controlled from the output of the glide path receiver I9 in a manner resembling the control of the horizontal pointer of the cross pointer meter shown in the prior patent of Percy Halpert, No. 2,502,721, dated April 4, 1950, for Instrument Landing Indicators (see Fig. 2). Likewise the twist or lateral inclination of the bar II is controlled from a second torque motor 20 connected to the spring centralized sleeve I4 and controlled generally from the localizer receiver. Since the index II is normally centralized when no radio signals are present, it may be used as the sole index for the gyroscope and index I omitted. In other words, the bank and pitch of the craft may be controlled by observing the relative tilt and up and down positions of horizon bar 9 and index bar II.

Preferably there is'introduced into the directional controls at least, not only a signal responsive to the departure of the airplane from the beam, but also the rate of departure. In other words, if it is desired to impart to the aviator a signal showing the rate and direction of turn necessary for best results, the rate of turn set in should be proportional to the sum of the displacement from the beam and rate of such displacement away from the beam, or a function of such rate. It is also known that a craft may be caused to turn by banking the craft alone, the rate of turn being a function of the banking angle and airspeed. In my device, therefore, I propose to introduce a tilt or bank into the index I I rproportional to the combination of the displacement from the beam and also the rate of change of such displacement. Since the latter, rate of change of displacement, is also a function of airspeed, the airspeed factor is thus, in large part, automatically taken care of, and also by designing the instrument for the airspeed usually employed in approach landing, the airspeed factor need not enter.

It has been found that when an aircraft is con` trolled in this manner, that is, making the instan- For up and down movement taneous rate of turn proportional to the sum of displacement and rate of displacement signals, the craft is capable of an asymptotic approach to the localizer beacon course. Thus if the pilot keeps the red bar II in line with the horizon line 9 on the gyro, he will make an asymptotic approachto the course merely by observing this single instrument and without having to refer to any additional cross pointer meters, directional gyros or turn indicators on the craft. 'I'his systern has the further advantage that cross winds do not cause an error, since the actual gyro heading is not shown but only the radio course.

For this purpose, I have shown in the Wiring diagram the D. C. signal from the localizer receiver 25 applied to a ring modulator 26, which is also supplied with A. C. to give a Variable A. C`. output which is amplified in amplifier 2l and supplied to the displacement amplifier 28 from which the signal is ledV to the torque motor 20. The rate of change of such signal is shown as obtained by also supplying the signal from ampli- Iier 21 to a suitable rate taking network. As shown this signal is first applied to the grid of electron tube 29, the output of which controls, through amplifier 38, a motor 3| driving a speed generator 32' giving an A. C. output voltage proportional to its speed and reversible in phase with its direction of rotation. The output of su'ch generator is induced in one of the two-phase windings 33 thereon, and is supplied to the rate amplifier 34 and combined with the output of the displacement amplifier 28 to control the motor 20. A feedback to the input of amplifier 30 is also provided from a transmitter 35 driven preferably at a reduced speed through step-down gearing 3S from the motor generator shaft 3l, such transmitter serving to normally oppose the signal from tube 29 and to wipe it out as soon as the angle through which the transmitter is turned becomes sufficient. Hence a speed signal only reaches amplifier 34 while the displacement is changing which is proportional to the rate of displacement change. Tube 29 acts to block any feedback into the displacement signal supplied to amplifier 28. The rate signal of generator 32 may also be fed back as a damping factor to amplifier 30, as shown diagrammatically by lead |33, but it will be understood that in practice separate coils 33" may be used as a feedback and as the rate signal source feeding into rate amplifier 34.

As indicated above, it is desired to govern the crafts heading in such manner that it will be broughtl onto the beam and kept there by altering the crafts heading in an amount such as to cause it to fly into the region of the radio beam Without overshooting.

Fig. 2 represents a second form of the invention in which the displacement signal from the localizer is combined with a signal representing the angular difference in azimuthal positions between the runway beam or beacon and the compass heading of the craft. The greater this angle, the greater the rate of change of displacement should be. As shown in the aforesaid patent of Percy Halpert, this may be accomplished readily by combining the output of the localizer amplierj derived from the output of localizer receiver 25 as in Fig. 1, for instance, with an output proportional to the difference in azimuth angular position or heading between the runway heading (or localizer direction in azimuth), which may be set in by a knob- 29 and dial 30 and the crafts heading represented by a compass 3. A radio guide for aircraft as claimed in claim 2, in which the means for controlling the aforesaid tilting means includes a component responsive to displacement of the craft from the radio defined course and a component responsive to the rate and direction of change of displacement of the craft from said course.

4. A blind landing indicator for aircraft as claimed in claim 2 in which the means for controlling the aforesaid tilting means includes a component responsive to displacement of the craft from the radio beam and a component responsive to magnitude and direction of departure between the localizer or runway heading and the crafts heading.

5. A radio-guided automatic pilot for aircraft having a, gyro-stabilizing means adapted to control the craft in elevation and bank, and through bank to control changes in heading, a radiodirectional receiver on the craft for modifying such controls upon departure of the craft from a desired radio course, said receiver including a means responsive to displacement of the craft from a. desired course in elevation for causing a change in indicated pitch of the craft whereby when apparently correcting the same, the craft is brought on the beam and means responsive 'to displacement of the craft from the desired radio course in azimuth for indicating a false bank whereby in correcting the same the autopilot changes the heading of the craft to eliminate such displacement.

6. A radio-guided automatic pilot for aircraft having a gyro-stabilizing means adapted to control the craft in azimuth, elevation and bank, and through bank to control changes in heading, a radio-directional receiver on the craft for modifying such controlsupon departure of the craft from a desired radio course in elevation for causinga change in pitch attitude to correct such displacement and means responsive to displacement of the craft from a desired course in azimuth for causing a change in bank of the craft to reduce such displacement, and means for modifying the azimuth correction in accordance with the angular difference between the crafts heading and the radio course.

7. A radio-guided automatic pilot for aircraft having a gyro-stabilizing means adapted to control the craft in elevation and bank, and' through said bank to control the craft in azimuth, a radio receiver on the craft, and means responsive thereto for altering the bank of the craft for altering its heading whenever the craft is off the radio course until the craft is back on the radio course.

8. In a radio blind landing indicator for aircraft having a glide path and localizer receiver. stationary and movable indices, an attitude gyroscope having a horizon marking thereon showing by its position relative to said indices both pitch and bank, means for altering the position of said movable index in pitch from said glide path receiver, and means for governing the tilt thereof in bank from said localizer receiver, whereby a change of attitude is indicated when the craft is off its radio course in azimuth or elevation, such as to indicate that the craft should be turned` toward its radio course.

9. A radio-guided automatic pilot for aircraft as claimed in claim 5,-Wherein said means for causing change in heading is also responsive to the rate of change of displacement in azimuth pilot for aircraft, a fixed direction maintaining means producing course signals, attitude maintaining means in elevation and bank producing elevation and bank signals,v a radio course receiver producing signals for modifying said other signals, servomotors controlling the elevator. ailerons and rudder, means for controlling the rudder servomotor during normal flight from said course signals, as modified by the signals received from said radio course modifying signals, and means for severing the control of said rudder from said. course signals during landing, and means for modifying the bank signals during landing from said radio coursesignals.

11. A night indicator for aiding radio guided landing approaches, the combination with a localizer or radio course receiver, and an attitude gyroscope, a pair of attitude indicators which are subject to relative tilting to therebyindicate the bank attitude of the craft, said tilting being in part controlled by said gyroscope, and means controlled from said receiver also for imparting relative tilt thereto in a, direction and proportional to the displacement of the craft from the beam or radio course whereby the aviator,l in apparently eliminating said tilt, reallyfbanks the craft proportionally and in a direction to turn the craft back on to the radio course.

12. In a, flight instrument for aiding steering of a craft in azimuth along a radio defined course, the combination with an attitude gyroscope,` and means for generating a, sense signal when the craft is oif the course to ther right or left proportional to the amount ofjoif course, means for supplementing said signal by a term varying with the rate of change of said signal, a pair of relatively tiltable attitude indicators, the relative tilt of which indicates the bank attitude of the craft, said tilt being in part controlled by said gyroscope andA in part by said supplemented sense signal, whereby the indicator falsely shows bank and the aviator in apparently eliminating the false bank actually banks the craft in-a direction and amount to cause it to return asymptotically to the radio course.`

13. A radio blind landing indicator for aircraft having a localizer receiver for guiding it in azimuth alongalocalizer'beam, a pair of relatively tiltable attitude indicators, an attitude gyroscope. the relative tilt of said indicators being jointly controlled by the output of saidlocalizer receiver and the position of the gyroscope about `the crafts bank axis, whereby a change of bank-attitude is shown by the indicators to the observer when the ycraft is off its radio course in azimuth, such as to indicate that the craft should'fbe banked in a direction to turn it back on to the beam course. I

14. A radio blind landing indicator for aircraft having a radio receiver providing a signal upon departure of the craft in azimuth from a radio defined course, an index normally fixed athwartship on the craft, an attitude gyroscope showing the bank of the craft by its stabilized position relative to said index, and means for tilting said index relative to the craft in bank from said signal in a direction to falsely indicate that the craft is banked with the right Wing down when the craft is to the right of its radio course and that the craft is banked with its-left wing down when the craft is to the leftof its radio course.

15. A radio blind landing indicator for aircraft, I

as claimed in claim 14, further characterized'by having means to proportion the amountof "tilt .imparted tol said index to both the displacement and rate of changeof displacement of the craft from its radio course.

16. In a radio blind landing indicator for aircraft having a glide path receiver, said indicator including an attitude gyroscope, a horizon indicator actuated thereby, a fixed reference and a movable index both adjacent said horizon indicator, thereby showing the pitch of the craft by the position of said horizon indicator relative to said reference or said index, and means for upwardly displacing said index from said glide path receiver when the craft is below the glide path and for downwardly displacing said index from said glide path receiver when the craft is above the glide path.

17. A fiight indicator for aiding radio guided landing approaches, the combination with a localizer or radio course receiver, an attitude gyroscope, a pair of attitude indicators which are subject to relative tilting to thereby indicate the bank attitude of the craft, said tilting being in part controlled by said gyroscope, and means controlled from said receiver also for imparting relative tilt thereto in a direction and proportional to both the displacement of the craft from its radio course and the rate of change of such displacement whereby the aviator, in apparently eliminating said tilt, really banks the craft proportionally and in a direction to bring the craft back onto the radio course asymptotically.

18. A steering aid system for manually piloted dirigible craft including means for providing a signal in accordance with the displacement of the craft from a radio iiight path, means for providing a signal in accordance with the first derivative of the displacement, means for coordinating said signals, and means operated by said coordinating means for indicating to the pilot the sense and amount of bank needed to restore the craft to its predetermined flight path.

ORLAND E. ESVAL.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,896,805 Sperry Feb. 7, 1933 2,266,410 Busignies Dec. 16, 1941 2,400,232 Hall May 14, 1946 2,423,337 Moseley July 1, 1947 2,502,721 Halpert Apr. 4, 1950 

